Process for the manufacture of armor-plates.



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.' Specification of LettcrsPatent.

Patented set. to, rare.

Application filed April 20, 1912. I Serial lilo. $32,144:.

"To all "whom it may concern:

' Be it known that I, ANGELO LUGERTINI, a subjectof the King of Italy, and residing at No. 69 Via Cristoforo Colo b0, Sampierdarena, Italy, have invents a certain new and useful eProcess for the Manufacture of Armor-Plates, of which the following is a specificationj This invention relates .to an improved process for the manufacturenf armor plates or. naval'and the likepurpo-ses based on the employment of a metal which h as'not yet follows 1. Manufacture of an ingot of Martin steel having approximately the followingchemical composition :Carbon 0.50 1500.7 0,

silicon 0.100 to 0.150, sulfur and phosphorus 0.035, manganese 0.25 to 0.40, chromium 1.80 to 2.50, nickel 3.50 to 4150.

The principal operation in the manufacture of steel which must always be borne in mind, isthe regplation of the temperature of the bath of molten metal by maintaining it at as low a. degree aspossible while yet su'ficient to allow and insure the complete fusion of .theffinal additions so thatthe metal can be run readily into the ingot molds. Any excess of temperature beyond -.what'is absolutely necessary for satisfying 'thoserequirements is'to be considered as in-' jurious to the mechanical properties ofthe .metal.

The steel ingot taken from the ingot molot is placed in a furnace and maintained therein at a. oonstanttempera'turd of about 450 degrees C; for a long period of several 'hoprs, said period varying with the "dimen sions of-the ingots- The length of time dur; gi-ng which the ingots remain in the furnace at a low temperature, varies in direct ratio withtheweight ofitheingots, commencing to with a minimum of: 25hours for small armor plateingots of about 12 tons weight each.

The said length of time is to be taken as a minimuni for ingots of almostround or rectangular form instead of the flat or'plate form usually adopted for armor plates.

The improved proc'essis carried out as The ingot is then placed in a furnace wherein it is heated for rolling or f org ng,

the heating beingefiected gradually until a uniform temperature of about -1200 degrees C. is reached. a i

at. The rolling or forging is efiected ref erably with the aid of repeated annealings and successive lowerings of the temperature of the whole plate down to about 4QO. -degrees (3., carried out in a stove or even in thamidst' of a mass of ashes.

5. The armor plate is now subjectedtmthe following series of thermal treatments;-

Heatingto a temperature of abouttiOQ dcgrees 6., and quenchingin oil or lukewarm water. Then heating to a temperature-pf from aboutj750 to 780 degrees (1, and upsetting of the armor plate, carebeingtaken, especially during this heating toelir'ninate by means of the press the most pronounced bends due to the rolling or, forgingepera tron, and whlch it is too risky to eliminate 'by heating to a low temperature. The armor plate thus upset is allowed to cool down to a uniform temperature ofabpu-t degrees (3., inoil or even in a tanlcof boiling water. It is thenimmediately placedtlie furnace, heated with care to a unifor n teinperature of about 630 deg eesC and oarcfull-y upset, after whicht armor platens allowed to cool freely in the air. Ttiimpre ferred to subject it to the mechanical operation, of planing onits face which isint'ended to be cemented; Although this planing is not absolutely neessary,.it ishowever-sutable for the purpose of removing the roughness and ariy other superficial faults that may heme wh silage forging operation.

ti. The armor plate is now subjected-tothe cementing operation which is efiected bygtlie use of cementing gases producedby special generating devices, or bythe use of mixtures of animal or vegetable .charcoahorby any o-thermethod, in a veryshort time, by keeping the plate 'm'contact withthece nenting agent during a eriod of about 60. hours at a temperature of from 960 to 1000 degreesC;

This short periodis sufiicient'to raise the face of the plate by a superficial percentage of 1 per cent. ofcarbon.

In. view of the exceptional shortness ofthe cementation period, the most suitable method which corresponds byits efiiciency to the. thermal requirements is the .rnethod' which is based on the use of carbonic oXid because this method has the great advantage of producing cementation to a depth which can be predetermined and of constant intensity at all oints thereof. On the termination of the cementation period the temperature is allowed to fall to about 780800 degrees (1., and the plate is immersed in oil until it has cooled down further to about 300400 degrees C. The armor plate is then placed in the furnace wherein it is heated gradually anduniformly to a temperature of 625-640 degrees (3., whereupon it is quenched in water.

The armor plate is then subjected to a second series of thermal treatments as follows :The-arm0r plate is heated to a temperature of 7 507 80 degrees 0., this temperature being utilized for bending the armor plate into its final form. As soon as this is completed, the plate, whatever its temperature may now be, is then placed immediately again into the furnace, heated to a temperature of 7 50-7 80 degrees 6., and again quenched in oil. The plate is removed from the oil while still hot, and it is immediately put back into the furnace wherein it is heated with care to a temperature of about 635 degrees C. It is then quenched in water.

After this operation the armor plate is machined to the desired shape after having first taken a sample from it by means of a chisel for breaking in the press for the purpose of examining the structure of the metal. The

armor plate is at the same time prepared for subjection to the final treatment of dif ferential hardening, portions being left at the ends as usual for the successive examination of its appearance after this operation.

Before proceeding to the final hardening, the appearance of the fracture after the last quenching at 635 degrees (3., is noted. If the fracture has a fibrous or approximately fibrous appearance, the final hardening is then proceeded with. If however the fracture has a'pearly or granular appearance the quenching in-water at 635 degrees 6.,

must be repeated. Finally the differential perature which is in contact with a bed of sand being heated to a temperature of about 600 degrees C. The plate is then quenched. What I claim is v 1. The process of making armor plate comprising the following stepszsubjecting the plate to repeated temperings, cementing the plate,'repeatedly tempering the cemented plate, heating the face of the plate above the recalescence point, while maintaining the back at a lower temperature, then quenching the plate.

2. The process of making armor plate comprising the following steps: annealing inoeaaae the steel ingot and after forging subjecting the plate to repeated temperings, cementing the plate, repeatedly tempering the cemented plate, heating the face of the plate abovethe recalescence point, a while maintaining the back at a lower temperature, then quenching the plate. I

3. The process of making armor plate comprising the following steps: heating a plate to 600 C. and quenching in water at 100 3., reheating to 750, cooling to 200 by quenching, cementing the plate, heating the cemented plate to 750 0., quenching; re-

heating to 635 C. and quenching; heating" the face of the plate above the recalescence point while maintaining the back at a lower temperature, then quenching the plate.

4. The process of making armor plate comprising the following steps: annealing the steel ingot and after forging subjecting the plate to repeated temperings, cementing the plate, repeatedly tempering the cemented plate, then heating the face ofthe plate to 850 C. while maintaining the back at a temperature not exceeding 600, then quenching the plate.

5. The process of making armor plate comprising the following steps: annealing the steel ingot and after forging subjecting the plate to repeated temperings, cementing the plate for/60 hours at a temperature of 960 to 1000 (3,, repeatedly tempering the cemented plate, heating the face ofthe plate above the recalescence point, while maintaining the back at a lower temperature, then quenching the plate. a

6. The process of making armor' plate comprising the following steps: annealing the steel ingot and after forging, heating the plate to 600 C. and quenching in water at 100 C.; reheating to 750 cooling to 200 by quenching, again heating to 630 for bending, cementingtheplate; heating the cemented plate to 7 50, quenching; reheating to 635 C. and quenching; heating the face of the plate above the recalescence point while maintaining the back at a lower temperature, then quenching the plate.

comprising the following steps: annealing the steel ingot'and after forging, heating the plate to 600 C. and quenching in water at 100 reheating'to 750 cooling to 200 by quenching, again heatingto 630 for bending; cementing the plate; heating the cemented plate to 750, quenching; reheating to 635 C. and quenching; heating the face of the plate to 850 while maintaining the back at 600, then quenching the plate.

8. The process of making armor plate comprising the following steps: heating the plate to 600 C. and quenching in water at 100 0.; reheating to 750 cooling to 200 by ing; cementing the plate for 60 hours in contact with carbon at a temperature of 960 1000; heating the cementetl plate to 750, quenching, reheating to 635 C. and quenching; heating the face of the plate to 850 While maintaining the back at 600, then quenching the plate.

9. The process of maln'ng armor plate comprising the following steps: annealing the steel ingot and after forging, heating the plate to 600 C. and quenching in Water at 100 C.; reheating to 750, cooling to 200 by quenching, again heating to 630 for bending; cementing the plate for 60 hours in contact with carbon at a temperature of 960- 1000; heating the cemented plate to 750, quenching, reheating to 635 C. and quenching; heating the face of the plate to 850 while maintaining the back at 600, then quenching the plate.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

ANGELO LUCERTINI. Witnesses:

Dunno NARVQNI, NICOLA 5mm. 

